Image sensors, such as CCD sensors and CMOS sensors, are widely known as image sensors used for digital still cameras, digital video cameras, mobile phone cameras, endoscope cameras, etc.
Currently, an image sensor having a layered structure, wherein a plurality of pixel electrodes are two-dimensional arranged on a substrate having a read-out circuit, etc., formed thereon, and an organic layer including at least a photoelectric conversion layer, and a counter electrode are formed in this order on the pixel electrodes, has been proposed (U.S. Pat. No. 7,920,189 (hereinafter, Patent Document 1)).
In the image sensor having a layered structure disclosed in Patent Document 1, the photoelectric conversion layer may be a continuous layer shared by all the pixel portions, or may be divided into parts corresponding to the individual pixel portions.
On the other hand, the image sensor provided with the continuous photoelectric conversion layer that is shared by the plurality of pixel electrodes has such problems that residual charges remain between the pixel electrodes and form a residual image of image information, and that the thickness of the photoelectric conversion layer is reduced at end portions of the pixel electrodes and electric field concentration occurs, resulting in leakage current, etc. In order to solve the above described problems, Japanese Unexamined Patent Publication Nos. 2008-177287 and 2009-259978 (hereinafter, Patent Documents 2 and 3, respectively), for example, propose providing the pixel electrodes having inclined end portions. Patent Document 2 teaches that it is preferable to incline the end portions of the pixel electrodes at an angle in the range from 30° to 120° relative to a planer substrate for suppressing occurrence of a residual image due to electric charges remaining between the pixel electrodes. Patent Document 3 teaches that it is preferable to incline the end portions at a predetermined inclination angle that is smaller than 90° for suppressing the decrease of the thickness of the photoelectric conversion layer at stepped portions of the end portions of the pixel electrodes and for suppressing occurrence of the electric field concentration.